Medical errors are recognized as a serious problem associated with the delivery of health care. The Institute of Medicine estimates that as many as 98,000 Americans die annually as a result of preventable medical errors. Medication errors constitute a critical component of medical errors in general. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) stated in the Nov. 19, 1999 Sentinel Event Alert, “Medication errors are one of the most common causes of avoidable harm to patients in health care organizations.” The 2001 publication “Retrospective Analysis of Mortalities Associated With Medication Errors,” Am. J. Health-Syst. Pharm., Vol. 58, Oct. 1, 2001, reported that among fatal medication errors, improper dose (40.9%) and administering the wrong drug (16%) were the most frequent. The FDA 2002 Performance Plan proposes the development of standards to prevent dosing and drug mix-ups.
Medication errors are attributable to one or more of fourteen causes that span the range from conceiving a therapeutic regimen to the delivery of a pharmaceutical compound. The top six mistakes, according to the Am. J. Heath-Syst. Pharm. article, constitute 80 per cent of all medication errors and are, in decreasing frequency, wrong dose, wrong drug, wrong route of administration, wrong patient, wrong rate, and wrong concentration. A number of commercially available products attempt to address the need to decrease the incidence of medication errors and are directed at various aspects of the possible mistakes. These products utilize software, drug libraries, and institutional limits placed on specific drugs.
For example, Alaris Corporation markets a software system named Guardrails™. Guardrails™ provides protection against infusion programming errors with tests of reasonableness during the initial programming and in subsequent programming of intravenous (IV) infusions. The system includes pre-programmed drug maximums that cannot be overridden by faulty bedside data input. The system, however, still leaves the potential for wrong drug, wrong patient, wrong rate, and wrong concentration errors.
Picis Corporation also offers medication management and data collection software trademarked as CareSuite™. An excerpt from its literature states: “Simply obtaining the infusion dose or rate from the intravenous pump would not be enough without automatically identifying the drug being administered. Thus the goal was to minimize computation and recording errors and give clinicians greater control over fluid management. With automatic data collection by CareSuite™ directly from the infusion pump, clinicians can be assured of accurate fluid infusions. Medical errors related to incorrect data entry and incorrect calculations are reduced.”
Systems like Guardrails™ and CareSuite™, while helpful in decreasing medication errors, all suffer from the same vulnerability, namely operator error. One such error arises, for example, when the wrong drug concentration, or even the wrong drug, is mixed by a hospital pharmacy. As the intravenous administration systems cannot identify the composition or concentration of an intravenous infusion, drug swap or admixture concentration errors are not prevented. U.S. Pat. No. 6,070,761 to Bloom et al attempts to deal with this problem during the vial loading process by standardizing and automating drug mixture and then verifying that the drug is the correct one for a given patient. Networking to one or more databases performs the verification. The system envisions various security and quality control features such as bar codes and passwords. Although this system may potentially lessen the likelihood of human errors, it cannot eliminate them, because it cannot positively identify the infusate.
Another unfortunate issue has been that of medical personnel deliberately administering unprescribed, dangerous, and even fatal types or doses of medication. One reported case resulted in the criminal conviction of a medical professional who administered muscle relaxants to ICU patients, resulting in a number of deaths. Currently, there is no system to automatically alert medical staff to this kind of danger. Errors of omission also occur in the administering of medications. As an example, such an error could occur when scheduled doses, whose timing is critical, are omitted or administered at unscheduled times. A system that automatically identifies the drug, time of administration, and dosing would serve as a quality control system to prevent inadvertent medication errors, as well as a deterrent to the deliberate misuse of the drugs or the omission of scheduled doses.
The pharmaceutical manufacturing industry, where real-time, on-line analysis of compounds is helpful for quality assurance and compliance with FDA GMP (Good Manufacturing Procedures) regulations, has automated systems that perform qualitative and quantitative analysis. These systems provide an automated analytical capability using spectroscopic analysis. A spectrometer passes a continuous portion of the electromagnetic spectrum through a specimen to develop an absorption spectrum. To establish a compound's identity, the absorption spectra can then be compared to spectral libraries of specific compounds. This identification process can be digitally automated. Quantitative analysis based on chemometric algorithms is then possible. The Beer-Lambert law, where all variables except concentration are known, can be used to perform the quantitative analysis. In present commercial applications, spectral databases use wavelengths in the range of 1-15 microns. The commercial devices, however are too large and too expensive for incorporation into clinical use.
Medical applications of spectroscopy are known. For example, Robinson, in U.S. Pat. No. 6,278,889, discloses a quantitative spectroscopic system to noninvasely determine in vivo glucose concentrations. Robinson also discloses the basics of quantitative spectroscopy. Unfortunately, Robinson's system is complex and costly due to 1) a variable path length and 2) a multiplicity of absorbing substances within the light path other than the analyte of interest.
U.S. Pat. No. 6,122,536 to Sun et al discloses an in vivo invasive infrared (IR) emitter and sensor for quantitative determinations of circulating analytes. The complexity of this system is due to the multiplicity of analytes and tissue components lying within a variable and, at times, a changing optical path length. The ideal situation for qualitative and quantitative spectroscopy exists when a single compound is suspended evenly in a relatively non-absorbing and spectrally known medium, and enclosed in a vessel relatively transparent to electromagnetic radiation and having a known spectral profile. Ideally, the vessel has a fixed, known optical path length. A fixed and known path length would, however, be unnecessary in systems utilizing Raman spectroscopy. Reflectance-based systems and qualitative systems without quantitative capability would also not require a fixed optical path length.
Rapid advancements in the areas of solid-state electronics, optoelectronics, and microprocessors have allowed the commercial production of high quality and inexpensive components in spectroscopic analysis. Various combinations of hardware and software can now perform rapid spectral data acquisition and analysis functions inexpensively. Medical and non-medical applications of these technologies are known. For example, pulse oximetry utilizes an LED-photodiode arrangement whereby two frequencies are sequentially passed through perfused tissue to determine oxygen saturation levels of hemoglobin. The transmittance ratios of these two wavelengths are then compared to an empirically derived and stored nomogram to determine the percentage of oxygen saturation. One example of such a device is U.S. Pat. No. 4,621,643 to New, Jr. et al.
The present wavelength range of commercial LED's is about 400-1,600 nanometers, or 0.4-1.6 microns. One example of an LED application, U.S. Pat. No. 5,995,858 to Kinast, discloses a phase-shifted, dual LED oximeter, which increases the signal to noise strength. The LED-photodiode probes used in the oximeter are the size of a band-aid and are inexpensive enough for a single, disposable use. Rosenthal, in U.S. Pat. No. 4,286,327, has devised an LED-based system for quantitative analysis of grain. McDonald, in U.S. Pat. No. 6,072,576, discloses an on-line, real-time Fourier Transformed near infrared (FTNIR) based system for process control in a chemical plant. Similarly, Ditmarsen, in U.S. Pat. No. 6,236,048, discloses a spectrally based system for characterization of a flowable material. Axon, in U.S. Pat. No. 6,362,891 discloses an FTNIR system for quality control of pharmaceutical tablet ingredients. It is noted that permissible tolerance levels of the ingredients are set for comparison to known levels, but thereafter unskilled operators are able to operate the system. Schnell, in U.S. Pat. No. 4,620,284, discloses a Raman-based system for qualitative and quantitative analysis using primarily a photodiode array for signal collection prior to comparison with known spectra.
To provide safer intravenous infusion would require that any qualitative or quantitative analysis of the infusate have some direct operative connection with the infusion process. Medications are often administered intravenously in a hospital setting utilizing a bag containing the added medication, an intravenous administration set, and an infusion pump. One conventional type of infusion pump system employs a peristaltic pump in conjunction with an intravenous administration set. The administration set consists of flexible thermoplastic tubing through which fluid flows from a suspended container, such as a flexible bag or rigid bottle, to a patient's vein. Much of the prior art relating to pumps is directed to delivering an accurate infusion rate, because an inaccurate infusion rate will lead to potentially dangerous incorrect doses of medications and fluids. One example of an infusion pump is U.S. Pat. No. 6,261,262 to Briggs et al. IV administration sets, such as U.S. Pat. No. 5,226,886 to Skakoon et al, provide tubing that carries the intravenous fluid through the infusion pump and to the patient.
Numerous models of IV infusion pumps and IV administration sets are commercially available. A typical system would be like that of the Horizon family of pumps and Horizon IV sets sold by B. Braun. All pumps in this family deliver infusions by positive pressure, which is generated through a volumetric displacement reservoir. This reservoir is incorporated within the IV administration set tubing, which is loaded into the pump via a door mechanism. The pump is set to run at a certain rate and activated. Alarms typically indicate some or all of the following problems: air-in-line, container empty, door open, downstream occlusion, hold time exceeded, low battery, low flow, system error, and upstream occlusion. Other common features include a dose/rate calculator mode, which automatically calculates the rate when dose information is entered, or the dose when rate information is entered. “Smart Pumps” can have preprogrammed institutional drug limits. The newest pump in the Horizon series, the Outlook™ incorporates bar code scanning technology to reduce drug administration errors. Even this technology, however, cannot account for errors such as incorrect admixture or incorrect labeling of the drug containers.
Ultimately, the existing safety systems related to intravenous infusion attempt to ensure that the right drug, in the right dose, is given to the right patient, with the right route of administration, at the right rate and strength, and at the right time. They all fail, however, because they lack a real-time ability to identify pharmaceutical or other compounds while these substances are being delivered to the patient. Such a system would further reduce medication errors. It would also permit data capture, storage, and analysis. Such a system could, for example, be integrated with a computer order entry system to form a complete feedback loop for quality assurance, maintenance of patient records, generation of bills, or even research and statistical analysis. It could, for example, eliminate the need for nurses to chart the administration of intravenous medications. At the present time, no mechanism exists that can perform these functions, because no automated mechanism exists for the qualitative and quantitative analysis of the drugs as they are intravenously provided to a patient.